Teresa green, thats a couple of interesting points you raise. At a rough approximation the tidal range in Ballina is around 1.7 metres, ive chosen Ballina as simply a random point on the north coast of NSW, it may be slightly more or less depending on where you are and its intended solely as an example. That 1.7m figure comes from here:
Ballina, Australia, Australia 7 Day Tide Chart - Tide-Forecast.com .The measured, observed change in sea levels is around +1.8mm to +2 mm per year, averaged and taken from tidal gauges since 1880. Satellite measurements done over the last 15 years or so indicate a slightly faster change of around +3mm per year, and this is also reflected in the tidal measurement figures. This statement makes no judgement on what causes these changes or what if anything should be done, it is merely a measurement. These figures come from a range of meteorological and scientific organisations that have been measuring for decades and in some cases centuries, long before concern about global warming became an issue.
Given the extremely small and slow changes that occur over decades or centuries relative to the much larger daily tidal changes you will see, unless you take highly accurate measurements at high and low tides and make corrections for tidal influence and other factors, it is extremely unlikely that an observer sitting on a rock with a fishing rod (and a beer in hand i hope
) will see any changes that cant readily be explained as daily tidal variations. In that 62 years if the sea level increased by 2mm/year there would be a change of 12.4 cm, from the day you first arrived there to this years fishing trip. This is approximately the same change as you would see in waiting a little less than half an hour while the tide was coming in. (assuming a 6 hour tidal cycle low to high, with the water level increasing evenly throughout that 6 hour period, a slight simplification but near enough for what we are looking at here.)
Do you believe that you would notice a very gradual 12 cm change over 62 years when each day you see a change of around +/- 1.7 metres, with waves and swell on top of these changes? I can understand how it is easy to say, entirely honestly, "I havent seen it happen", but I think given the timescales and sizes of the changes, you wouldnt see it without making use of tidal gauges and recording measurements over decades, which is what a few organisations have done. This is a major weakness with the "I havent seen it, therefore it isnt happening" argument. Also, everyone in your group of friends and colleagues agreeing with you is not really a strong argument - in any political party or social/religious organisation (left, right, fundamentalist christian/muslim/atheist, crypto-fascist bourgeois commie
) you will find groups of people in furious agreement with one another on many things, but that doesnt necessarily make them correct, or even remotely connected to reality. Im not suggesting this is the case with your group, just that people agreeing on something doesnt automatically make all those involved correct.